Comment by mirsadm
3 months ago
It is incredibly annoying that instead of adopting JpegXL they decided to use UltraHDR. A giant hack which works very poorly.
3 months ago
It is incredibly annoying that instead of adopting JpegXL they decided to use UltraHDR. A giant hack which works very poorly.
That's backwards compatibility for you.
I think Ultra HDR (and Apple's take on it, ISO 21496-1) make a lot of sense in a scenario where shipping alternate formats/codecs is not viable because renderer capabilities are not known or vary, similarly to how HDR was implemented on Blu-Ray 4K discs with the backwards-compatible Dolby Vision profiles.
It's also possible to do what Apple has done for HEIC on iOS: Store the modern format, convert to the best-known supported format at export/sharing time.
> A giant hack which works very poorly.
Indeed. I tried every possible export format from Adobe Lightroom including JPG + HDR gainmaps, and it looks... potato.
With a narrow gamut like sRGB it looks only slightly better than JPG, but with a wider gamut you get terrible posterization. People's faces turn grey and green and blue skies get bands across them.
Meanwhile my iPhone creates flawless 10-bit Dolby Vision video with the press of a button that I can share with anyone without it turning into a garbled mess.
Just last week I checked up on the "state of the art" for HDR still image sharing with Gemini Deep Research and after ten minutes of trawling through obscure forum posts it came back with a blunt "No".
We've figured out how to make machines think, but not how to exchange pictures in the quality that my 12-year-old DSLR is capable of capturing!
... unless I make a YouTube video with the images. That -- and only that -- works!
JPEG XL supports UltraHDR.
JPEG XL's normal HDR capabilities were not harmed in the process when UltraHDR was added.
It was added for reaching parity with JPEG1 and HEIF/AVIF for the needs of UltraHDR developers and believers.